This project is a continuation of our studies of increment thresholds in young human infants. The major thrust of the project is to develop techniques for gaining rough control over the retinal eccentricity of stimuli presented to infants. A "fixation and flash" technique is being developed. In this technique, the infant's attention will first be drawn to a central fixation pattern. A stimulus will then be presented for 500 msec or less, at a specified eccentricity, to the left or to the right of the fixation target. The forced choice preferential looking (FPL) method will be used for data collection. The first experiment conducted will concern the development of spatial summation, at various retinal eccentricities, in infants from one to four months of age. Later studies will be concerned with the variation of color vision in different retinal regions.